Control apparatus



' April 18, 1944- l.. o. GRONDAHL ETAL' 2,346,748

CONTROL APPARATUS Filed Oct. 8, 1941 l Tb-320ml? E295. DIffl Patented Apr. 18, 1944 vLars O. (rrondalfil,x

Pittsburgh. and laul N..Y

, Bossart, Gheswick, Pa., assignors to The Union Switch t Signal. Company,

Swissvale, Pa., a

corporation of Pennsylvania- Application, October 8, 19.41. Serial No., 414,100.

(Cl. 2id-124') 7 Claims,...

Our invention relates to controt apparatus, and it has particularv referencey to the. organization of such apparatus into control systems for railroads arranged to provide at a given point a warning or indication thatl a. train is approaching such point.

It has been proposed heretofore to provide apparatus for approach controlling or indicating, in cases where the control or indication required is an essential element of a permanent signaling system, by means permanently installed as a portion of the signal system and usually involving track circuits together with the necessary insulated rail joints., At times, however, it is desirable temporarily to approach control or indicate the approach ofv a train at a given point, as for example during the` time that a Aconstruction or maintenance crew is working on a given section of track, or for the period that relatively heavy highway traiic is caused to travel an unprotected crossing, ordinarily handling a small amount of traiiic, due to a detour on a main highway. In these latter cases, the expense of installing insulated joints, and in the accompanying interference with traffic moving over the track during the insulation of the joints, may not warrant the use of the usual track circuit apparatus for controlling the approach warning or indication devices.

It is an object of our present. invention to provide systems involvingv readily portable and easily installed apparatus arranged to provide an approach control or indication when a train approaches aV given point on a trackway.

Another object is to provide means arranged to be independent of the usual track circuit apparatus and functioning to provide a warning or indication when a train approaches a given point on a trackway.

Anadditional' object is toy provide an approach control system involving readily portable, easily assembled apparatus arranged to avoid the necessity of using line wires. or cables extending along the trackway.

A further object is to provide novel and im proved approach control and' indication systems.

The above-mentioned and other important objects and characteristic features which will become readily apparent from the following description of' our invention, are attained in accordance with the invention by utilizing a track instrument, operatively associated with a rail of a stretch. of" track, for connecting a source of current through the'contact of the instrument to a relay at a point remote from the Cil source. inA a. nonetrainfshuntablo; track, circuit i;ncluding` at least` one rail of; the stretch and a conductor; The conductor may comprise an earth; or,V ground; connectiom or may. as in the oase ofu a. stretch;Y oi multiplo track road, 0.0mp-rise a track. rail of: another track of Such road- We shall describe; several forms of apparatus embodying our invention, and shall then point out the novel teatures thereof in claims.

In the accornpanyir-igl drawing, Fig. 1 is a diagrammatic View showing one form of apparatus embodying our invention. Fig. la is a sectional ViewA of; aI track` instrument` forming part of the apparatusl illustrateclin Eig. 1. Figs. 2,13 and 4 are diagrammatic views illustrating modified forms of the apparatus represented in the drawing, and each; embodying our invention. In each of: theV several views, similar reference characters have been employed to designate corresponding parts.l y

t'teferringl to Fig, l, the reference character X designates a stretch of railway track over which trafc normally moves in the direction indicated by an associated arrow, or from left to right as viewed in the drawing. Operatively associatedA with a rai/lof the stretch is a track instrument, designated by: the reference character M, having a contact which is operated by a; vertical movement of` the rail or a blow of the wheel. Instrument M may be of any suitable form and for the purposes of the present description we shall assume that instrument M is of theA microphone type described and claimed in Letters Patent of `the .United States No. 1,834,077, granted December 1,1931, to A. J. Sorensen. Referring particularly to Fig. 1a., a track instrument M of the` microphone type is represented attached to a rail by means of a clamp t which is secured vto the base of the 4rail by a lug 3 and a bolt 5. The microphone comprises an `insulating housing 6 attached to clamp .Il by af screw l, and which housing contains two spaced vertically disposed metal electrodes 8 and 9. The space between these electrodes is at least partially lled with carbon granules m, and` the parts are so proportioned that under the conditions when microphone M is .not vibrated, theresistance between the electrodes 8 and 9 through` the carbon granules is relatively low, but when the microphone is vibrated; and the carbon granules are agitated, the resistance between the two electrodes is greatly increased.

'instrumen-t M has Vits, contact, comprising the electrodes and carbon granules, interposed in the circuit connection of a source of current, such as battery 2, across a conductor and but one track rail of stretch X, and a relay R is connected across the one rail and the conductor at a point remote from the source. When instrument M is not Vibrated, suflcient current flows through the instrument, the one track rail, relay R andthe conductor to energize the relay, but when instrument M is actuated by a train and its carbon granules are agitated, the resistance between electrodes 8 and 9 increases to cause in turn the current iiowing through ductor to decrease to a value below that required to hold up relay R. Relay R at this time is caused to'j release and close its back contact II to complete an obvious energizing circuit, including a source of current K may, for example, comprise a highway crossing signal, or as shown may comprise an indicator for warning track crews or gangs of the approach of a train. -It follows that when a train on track X actuates track instrument M, relay R is caused to release and indicator K is energized to indicate that a train is approaching. After the train passes the track instrument, relay R of course becomes energized to deenergize indicator K and restore'the apparatus to its normal condition. Y y f The'conductor forming a portion of the circuit of relay Rv may, as indicated in Fig, 1, be a ground or earth path havingV a groundrtermnal GI, or as represented in Fig. V2, the c onductor may be a rail of a second track XI of a multiple track railroad.v In either case, the circuitof relay R employs a single rail of any one track and is arranged to avoid the necessity of line wires or cables extending along the trackway. l Referring nowto Fig. 2, a second track instrument MI is represented operatively associated with a rail of a second track XI, and both instruments M and Ml of Fig. 2 cooperate in controlling an obvious circuit for a tranic responsive relay MR. If desired, however, relay MR may be arranged to be responsive to trac on either one but not both of the two tracks,y in which event only the one track instrument associated with thev selected one track wouldbe employed. Relay MR is energized when the track instruments are unactuated, and relay MR closes its front contact I5 to connect a suitable source of altervnating current, such as a generator not shown in the drawing but having its opposite terminals designated by the reference characters BX and CX, to primary winding I6 of a transformer I1. Secondary winding I8 of terminal connected to a selected one of the track rails of stretch X and has its other terminal connected to a selected one track rail of stretch XI.

Relay R is connected across the selected one track rails of the two tracks, over a stick circuit including its own front contact 20. Relay R may be of the alternating 'current type directly responsive to the alternating current impressed by transformer I1 across the selected rails of the two tracks, or as shown relay R may be of the direct current type, in which event a rectier 2I is interposed in the connection of the relay to the track rails for rectifying the alternating current into and supplying relay R with rectified current. Relay R controls an associated indicator K over its back contact II, and is arranged so that when once released due to a train actuating either one of the track instruments M and MI, relay R opens its front contact to interrupt its circuit at that point. An acknowledging switch AS is the track rail and contransformer I1 has one I2, for a device K. The device y provided'75 and may be closed to provide an alternate patharound front contact 20 in the circuit of relay R, and it follows that when relay R is released, it remains released until track instruments M and MI become inactive and acknowledging switch AS is closed. When these conditions exist, relay R picks up and closes its yfront contact 20 to complete its previously mentioned stick circuit, whereupon acknowledging switch AS may be opened and the apparatus is restored to its normal condition as represented in the drawing.

The rails of stretches X and XI may, as shown in Fig. 2, be divided by insulated joint j at a point intermediate the connection of the source and relay to the track rails. The current from source BX-CX may be transmitted around these joints to relay R by any suitable means, as by a transformer 23 having its primary winding 24 connected across the selected rails of tracks X and XI on one side of the joints and having a secondary winding 25 connected across the selected track rails on theopposite side of the joints. i

The apparatus vembodying our'invention may also be employed on a track over Which trafiic travels in either direction, and be arranged so as to provide a Warning or indicationwhen a train approaches a point on the trackway'but not when it recedes from such point. Such an arrangement is represented in Fig. 3, and it employs interlocking relays, designated by the reference character XR with suitably distinguishing sufiixes. These relays may be of any suitable type such as, for example, the type disclosed in Letters Patent of the United States No. 1,799,629, granted on April '1, 1931, to W. K. Lockhart and T. J. OMeara. These relays are well-known and comprise two windings WI and W2 and an interlocking mechanism which cooperates with the armature of the windings ln'such manner that when winding WI 'is the rst of the two windings to -be deenergized, its armaturereleases and its front contact 21 becomes opened, but when winding W2 vis the firstA winding to be deenergized, the interlocking mechanism is caused vto latch up the `armature of winding WI and prevent front contact 21 from opening when winding WI is subsequently de-energized during the interval that winding W2 is still deenergized. When front contact 21 of winding WI is closed, a suitable source of alternating current, such as a generator, designated by the reference 'character f I, and generating lcurrent having a preselected frequency, hasone terminal connected to one rail of track X and has its other'terminal connected to one rail of track XI. f t

Referring toFig. 3, interlocking-'relay XRI is representedv as being employed for. providing van approach control or indication when trains operate on tracks X and Xl in theA eastbound direction, or from left to right as viewed in the drawing. Winding WI of relay XRI is. energized over an obvious circuitvgoverned by instruments M and MI, while winding W2 of -`relay XRI is energized over another obvious circuitgovernedby'instruments M2 and M3, which instruments are operatively associated one with each track of the represented double track road'. v Instrument M2 is located along the trackway at a point such that it will be actuated by an eastbound train after such train has actuated instrument M associated with the same track X, while instrument .M3 is likewise located alongftrack XI at a point 4where it will be actuated subsequent to an eastbound train on track XI actuating the other instrument MI I-At `.thele-elected'.point onfthetrackway where it is desired: to provide.fantirfdicati'om :a relay Rl is connected across ltheiselectedrails of tracks 2X sand` XI fthroughfiatuning .unit :'IUI sand .a .transformer'Z .Transformer 8 fhasiitsprimary Windcorresponding to fthefrequency of current. supplied from the source fl and a rectierior; rectifying such 'current .into :and 'supplying relay Rl with 'unidirectional current. It Fis apparent, 'therefor-e, that 'when'front fcontact :2l oi winding WI fof re1ayXRLtis'closed, relay Rl :is-energized by currentrf the'. selected .frequencysupplied'from theisourcefi. When relayRlis released,.its back `contact l! completes an "obvious `energizing'foirlcuit for 4anassociated'.indicator Another interlocking relay .XR2 is employed forenabling an indication .to'be provided Whentrafiic :operating in'thefother Tor Westbound direction `onthe tracks X` and .X I .approacheszthe selected point. WindingsWl tand W2 of relay XR2 are controlledin a mannercorrespondingto that pointed outin d'etailfor relay .XR'L and when front contact :21 0f winding WI :of relay XRZ is closed, .it connects v`aisource of current, distinctively different fromthe source -f,zacross one railfo'i track 'Xsiand 'one rail of track .XL

The sourceofcurrent associated WithrelayfXRZ may be unidirectional .rin character, or as .shown may `comprise a generator :generating: current having fa `iirequencydistinctively dierent "from fthe I'fr'equency of current .generated .by l'source fl To detect this distinctively :different current, fa` `relfaylftfl Lis providedrattherselected.point and is connected'througha:second tuning iunit .T112 to secondary `windingllil of relay:R2. '.Tl'reunit TUZ -is-a resonant rectier unit tuned to resonance at -fa frequency corresponding :to `the frequency of i Jcurrent 'supplied from the :source lf2. L'If, however, thesource 'f2 iis a `source o'f unidirectional current,fthen unit TU'Z would be dispensed with, and relay R2 would be connected to the one rail lottrackLSQanrltO-the one rail of track -Xl through fafdirect connection Whichmay include a reactor fforblocking vthe yiiow df alternating currentfsupyplied ffrom the source fl. Relay R2 vwhen re- `'leased/completes' at its back contactZ-an obvious energizing 'circuit I'for a device, Which-may be in- A'dicator K associated with relay Rl, or as shown may be a second indicator Kl. As W'ill'be made clear presently, the advantages of using twoinicators, K and KI, onefor each 4relayRl and R2 isrthat the two indicators permit the-directionfof the 'approaching train to be indicatedfwhereasza single indicator would only signify ythat -a train is 'approaching yandwouldy not indicate the 4direc-- `tion of movement of such train.

VWhen an eastbound train operates `on leither rtrack X or Xl, 'winding WI of relay XR! is caused to releasewhen'th'e train aetuates instrumentM orMl, as 'the case maybe. 'Winding'WZ also is released when such train actuates .the other track instrument M2 or M3, but since winding'Wl Was rst released, .its iront Contact 21 opens to disconnect the source ,fl from the one rail .of tracks 'X and Xl. Relay Rl according'ly releases and 'indicator"Kbecom'esenergized f .to indicate for Warnthat ian :eastbound train .is

"approaching,

After :the train passes the .locationof instru- :ments M.'andlM| 'associated with relay XRI, winding Wl .of;relay;XRl picks up andcloses its -frontcontact'Z'l toreconnectithe source ,f I iacross the rails of tracks X and XI, and relay Rl accordingly becomes energized and-'opens its back icontact 'Il to deenergize .indication device K. Then, When the train `passes the locationof the y'other instruments, M2 and M3, associated with .'relay XRI', the "other Winding 'W2 becomes energized and relayXRl accordingly is restored to its normal condition.

leased to cause the .interlocking 'mechanism of y .Winding`r subsequently. becomes released due tothe lsociate'd instruments M contact 21.

but not `bothof the tracksf by'instrument M2, While the `controlled byinstrument :would insure that a .proper indication is `proactuationtof instrument Mor Ml. .The source f2 .associated with relay mZ'accordingly isnot dis- .connected from the track rails atthis time, hence relay R2 remains energized and it .follows 'that an eastbound train .does not cause a'second indication to be exhibited when such train recedes from theselected point. Windings lWZ'and WI arefof course,rcaused"to become energized in the order named "when Athe Ytrain clears the vinstruments associated :with relay XR2, andthe apparatus accordingly is restored toits .normal condition as represented inthe drawing.

'When a westbound 'train operates over either trackX or XI, indicator Kl is .caused vto fbecome energize'dby'the"apparatus of' Fig. 3 in a manner believed 'to be obvious from 'an inspection ofthe drawing, an'dfurther detailedexplanation is believed to be unnecessary.

"There is .fa :remote possibility .that the apparatus represented in Figi-3 might not function'to provide an indication of :an Aapproaching train when `trains:operatingz'in opposite directions on tracks`X and XI pas's'the track instruments 'associated With'one offthe relays XR, for example, should a `receding eastbound 'train on track'XI vstartto pass instruments M3 and MI 'associated with relay XE2, just prior "to a westboun'dtrain on track "X reaching thelocationof the-other asland M2, then Winding W2 Would-be rst released and would latch up -windingW'l to prevent the `opening of its front 'Thisfobviously prevents release of relayRZ Vand hence would lnot aiord an indication that the westbound train is approaching.

`If`it is desired to guard againstthis contingency,

another interlocking relay may be lassociated with relay XE2, and such interlocking relays may be arranged to be controlled by trahie on .only one Thus, V'for example, relay'XR'Z might ihaveits winding W! controlled by :instrument M andlits winding W2 vcontrolled other relay .would have one of 'its windings controlied by instrument Ml and itsother Winding controlled .by instrument M3. 'The circuit connection of :source f2 to the one rail of each trackX and .XI would then be carried over .front .contact .2'.1 of relay XE2 connectedinaseries Withafrcnt contact of the one Winding'of the other.interlocking .relay M i .This arrangement vided .at .all times when la Westbound train on either track approaches the location of relay R2. In like fashion, a second interlocking relay may be associated with relay XRI and the two interlocking relays may be arranged in the manner described to provide an indication whenever an eastbound train on either track approaches the location of relay RI.

In Fig. 4, relay MR is controlled by an associated pair of instruments M and MI, and a second relay MRI is controlled by another pair of instruments M and MI. Relay MR, when picked up, completes at its front contact 35 an energizing circuit for an oscillator 36, which oscillator has one of its output terminals connected to a center terminal of a resistor 31 connected to the two rails of track X in multiple, and has its other output terminal connected to a center terminal of another `resistor 38 connected across the two rails in multiple of the other track XI. Similarly, relay MRI controls at its front contact 39 an obvious energizing circuit for an oscillator 40, which oscillator has its output terminals connected, one to the two rails in multiple of track X and the other to the two rails in multiple of track XI. The frequency of current supplied from oscillator Ml is distinctively different from the frequency of current supplied from oscillator 36.

An amplier 42 is inductively coupled with the rails of tracks X and XI by means of pick-up coils 43 disposed in inductive relation to the rails of tracks X and XI, and amplifier 42 supplies energy through tuning units TUI and TU2 to relays RI and R2, respectively. Unit TUI is tuned to resonance at a frequency corresponding to the output frequency of oscillator 3E, hence relay RI is energized and picked up when front contact 35 of relay MR is closed. Unit TUZ is tuned to resonance at a frequency corresponding to the output frequency of oscillator 40, and relay R2 is energized and picked up when front contact 39 of relay MRI is closed. The frequencies of current generated by oscillators 36 and 40 preferably are in the range of from 1000 to 10,000 cycles a second, and such high frequency currents are transmitted through the rails substantially independent of insulated joints in the rails. Circuits of the type illustrated are well-known and have been proposed heretofore for use in train communication systems.

When a train actuates either instrument M or MI associated with relay MR, that relay is caused to release, oscillator 36 becomes deenergized, and relay RI accordingly releases to complete an obvious circuit for indicator K. After the train passes the location of instruments M and MI associated with relay MR, that relay picks up and oscillator 36 becomes active to cause relay RI to pick up and deenergize indicator K. In like fashion, when the train passes instruments M and MI associated `with relay MRI, that relay is released, oscillator 40 is deenergized, and relay R2 accordingly is caused to release to energize indicator KI After the train clears instruments M and MI associated with relay MRI, that relay picks up and restores the apparatus to its normal condition, as represented in the drawing.

It is, of course, to be understood that the di rectional means provided for the apparatus of Fig. 3 may be incorporated into the apparatus of Fig. 4, whereupon indicator K may be energized only when an eastbound train actuates either instrument M and MI associated with relay MR, and indicator KI may be energized only when a westbound train'actuates either instrument M or MI associated with relay MRI. In addition, it is to 'be noted that while the two rails of each track are employed in multiple in Fig. 4, the system may be arranged to employ only a single rail of each track, or if desired, but a single rail of one track and a ground return path.

Although we have herein shown and described only a few forms of control apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

l. In a warning system for railways, the combination with a stretch of double track railway, means responsive to trafiic operating on either of said tracks, a warning device, a relay for operating said warning device, and means governed by said traffic responsive means for energizing said relay over a circuit including at least one track rail of each of the two tracksl of said double track railway.

2. In combination, a stretch of double track railway, means responsive to traffic on eitherof said tracks, a source of current, a circuit Acontrolled by said traffic responsive means for connecting said source across one rail of each of said two tracks, a relay connected across the said one rails of said two tracks over a circuit including its own front contact, warning means governed by said relay, and restoring means for at times providing an alternate path around said front Contact in its said circuit of said relay.

3. In combination, a stretch of double track railway, two track instruments one for each track of said railway, each track instrument operatively associated with a rail of its associated track, a source of current connected across one rail of each of said tracks over a circuit governed by each of said track instruments, a relay controlled by current derived from said one rails of said two tracks,` said relay normally being energized over a circuit including its own front contact, a warning device controlled by said relay, and a manually operable switch for at times completing the circuit of said relay around its said front contact.

4. In combination with a stretch of double track railway, a relay connected across one rail of each of said tracks, a source of current connected across the same two rails at another point, and means interposed in said last mentioned connection and responsive to traiilc on either of said tracks for controlling the connection of said source to said rails.

5. In combination with a stretch of railway track having two groups of two track instruments operatively associated therewith at spaced points, two relays at a point along said track intermediate the locations of said two groups of instruments, a first source of current connected to one of said two relays over a first circuit comprlsing one track rail and a conductor not comprising the other rail, a second source of distinctively different current connected to the other of said two relays over a second circuit comprising said one track rail and said conductor not oomprising the other rail, means interposed in said first circuit and controlled by the instruments of one of said groups for interrupting said first circuit when said one group track instruments are actuated by a train operating onl said track in one direction but not the other, and means interposed in said second circuit and controlled by the instruments of the other of said groups for interrupting said second circuit when said other group track instruments are actuated by a train operating on said track in the other but not the one direction.

6. Directional warning means for indicating at a selected point along a stretch of railway track the approach of a trainin either direction, said means comprising two sources of current of distinctively diierent character, relay means located at said selected point selectively responsive to currents of said dilerent characters, a common circuit means including at least one of the rails of said stretch for supplying currents from said sources to said relay means from points disposed on opposite sides of said selected point when no train is approaching, means for interrupting the supply of one only of said currents to said relay means when a train approaches said selected point in one direction and for interrupting the supply of the other only of said currents when a train approaches said selected point in the other direction, and warning means selectively controlled by said relay means.

7. Directional warning means for indicating at a selected point along a stretch of railway track the approach of a train in either direction, said means comprising a circuit including one only of the rails of said stretch, track instruments operatively associated with said stretch on opposite sides of said selected point, means separately controlled by each instrument for vim pressing on said circuit when no train is in the vicinity of the instrument a current which is distinctively different from that impressed on the circuit under the control of the other instrument and for interrupting such current when a train is in the vicinity of the associated instrument, and means receiving energy from said circuit at said selected point and selectively responsive to the different currents for controlling warning devices located at said selected point.

LARS O. GRONDAHL. PAUL N. BOSSART. 

